Absorbent gelling materials (AGM's) are polymeric materials which are capable of absorbing large quantities of fluids such as body fluids and wastes and which are further capable of retaining such absorbed fluids under moderate pressures. These absorption characteristics of absorbent gelling materials make such materials especially useful for incorporation into absorbent articles such as disposable diapers, incontinent pads and catamenial napkins. For example, Procter & Gamble; European patent application EP-A-122,042; published Oct. 17, 1984 discloses absorbent structures wherein discrete particles of absorbent gelling material (hydrogel particles) are dispersed in a web of hydrophilic fibers. Additionally, U.S. patent application Ser. No. 734,426 filed on May 15, 1985, now U.S. Pat. No. 4,673,402 issued June 16, 1987, by Paul T. Weisman, Dawn l. Houghton and Dale A. Gellert discloses an absorbent article having a dual-layer absorbent core wherein a shaped core component consists essentially of hydrophilic fiber material and an insert core component consists essentially of a substantially uniform combination of hydrophilic fiber material and discrete particles of absorbent gelling material.
However, several difficulties have been encountered in airlaying absorbent cores having a multiplicity of layers and/or layers containing a mixture of fibers and particular amounts of discrete particles of materials such as absorbent gelling materials. Airlaying apparatus and methods require the removal of the gas or air which transports the fiber/particle admixture from beneath the foraminous forming element of the airlaying apparatus. During this removal, small particles which are mixed with the fibers can generally be drawn along with the air through the voids in the foraminous forming element, resulting in a loss of expensive absorbent gelling materials through the airlaying apparatus, the resultant absorbent article also having a reduced quantity of absorbent gelling material dispersed throughout its absorbent core resulting in a loss of absorbent capacity in the articles. Additionally, relatively large particles tend to plug or block the flow of air through the foraminous forming element resulting in a loss of uniformity of basis weight across or along the fibrous web or absorbent core as well as machinery down time necessitated in order to unplug the foraminous forming element. Thus, it would be advantageous to provide an airlaid fibrous web having discrete particles of material, such as absorbent gelling materials, dispersed through at least a portion of the web without having reduced design quantities of materials in the core and with uniform basis weights across or along the material-containing layer of the web.
Accordingly, it is an object of the present invention to provide airlaid fibrous webs having discrete particles dispersed through at least a portion of the web.
It is a further object of the present invention to provide an absorbent core wherein fibers or fiber/particle admixtures are airlaid over a dusting layer to minimize loss of particles, to provide more uniform and efficient cores, and to provide more efficient and effective use of absorbent gelling materials.